Figure 2.

IL-12-deficient mice aremore susceptible to UVB-induced activation of NF-κB/p65 and NF-κB-targeted proteins. (A) Long-term UVB exposure of the mouse skin enhances the activation of NF-κB and IKKα, and this effect is greater in the skin of IL-12 KO mice than that of WT mice. (B) The activity of NF-κB in the nuclear fraction of epidermal lysates was measured using NF-κB/p65-specific activity assay kit, n = 6. (C) UVB-induced activation of NF-κB-targeted proteins, such as iNOS, cyclin D1, PCNA, and COX-2, is greater in the skin of IL-12-deficient mice than in their wild-type counterparts. Epidermal skin lysates from long-term UV-exposed WT and IL-12 KO mouse skin were used for Western blot analysis. The expression levels of these proteins were also compared with non-UVB-exposed age-matched control mice. A representative blot is shown from three independent experiments with almost identical observations. (D) The total epidermal mRNA expression of PCNA, cyclin D1, COX-2, and iNOS was determined using real-time PCR as described in the Materials and Methods section. The results are presented as the expression of the individual mRNA with normalization to β-actin using the C_t method, n = 6. Skin samples from age-matched mice that were not UV irradiated were used as a control. Significant difference versus UV-exposed WT mice, *P < .01; **P < .005.